Circulated bills or notes used in currency, coupons and the like are subjected to many adverse conditions which eventually make them unusable. Excess wear of the bills often leads to tears and holes in the bills. Also, the lengths and widths of the bills may be made shorter by portions of the bills being worn or torn away, or may be made longer by repairs such as taping or stapling two separated pieces. Sometimes the corners of the bills are missing or folded. All of these conditions require that the bills be taken out of circulation.
Various systems have been used for detecting the characteristics of bills. These have been used in money changers and vending machines. Because the general acceptability of bills decreases as they drop below standards of nominal uncirculated bills or notes, it is desirable to provide a single system for inspecting and rejecting bills for the most commonly found defects.